Shapes in photoshop

Choose a Foreground color.

Select the Rectangle tool.

In the Options bar, choose Shape.

Drag your cursor to create a rectangle. A new layer will automatically be created and the shape will fill with the Foreground color.

Select the Add Anchor Point tool.

Click the top edge of the shape to add a point.

Switch to the Pen tool. Hold down Alt/Option and click on the new point.

Choose the Direct Selection tool.

Click on the new point and drag it down. (The point should look filled in and the other points should look hollow.)

Use the pen tool to create a path of that shape.  Convert the path to a selection. Fill the selection.